Technical Field of the Disclosure
The disclosure generally relates to internal combustion engines and exhaust gas recirculation (“EGR”) systems of such internal combustion engines. More specifically, the disclosure relates to an EGR power module for controlling the EGR systems of internal combustion engines and methods of use thereof.
Description of the Related Art
In internal combustion engines, exhaust gas recirculation (“EGR”) is a process where nitrogen oxide (NOx) emissions is reduced and is used in both standard gasoline and diesel engines. NOx is produced in a narrow band of high cylinder temperatures and pressures. EGR systems work by recirculating some of the engine's exhaust back to the engine cylinders. Exhaust is moved back into the combustion chamber when the exhausted air is much hotter than the intake air. EGR systems work by diluting the N2 and providing gases inert to combustion (CO2 primarily) to act as an absorbent of combustion heat to reduce peak in cylinder temperatures.
In an EGR system for a diesel engine, the exhaust gas replaces some of the excess oxygen in the pre-combustion mixture. Because NOx forms primarily when a mixture of nitrogen and oxygen is subjected to high temperature, the lower combustion chamber temperatures caused by EGR may reduce the amount of NOx the combustion generates, which consequently causes some loss of engine efficiency.
Most modern engines now require EGR to meet emissions standards. However, EGRs appear to be a very expensive technology over the long haul for reducing NOx emissions. In modern diesel engines, the EGR gas is cooled with a heat exchanger to allow the introduction of a greater mass of recirculated gas. Unlike standard gasoline or spark-ignition engine (“SI” engines), diesels are not limited by the need for a contiguous flame front. Furthermore, since diesels always operate with excess air, they use EGR rates as high as 50%. For example, at idle when there is otherwise a large excess of air in controlling NOx emissions, it has been discovered that exhaust recirculated back into the cylinder can increase engine wear as carbon particulate wash past the rings and into the oil.
Since diesel engines are unthrottled, it has been discovered that EGR does not lower throttling losses in the way that it does for SI engines. Exhaust gas, largely carbon dioxide and water vapor, has a higher specific heat than air, so it still serves to lower peak combustion temperatures. However, it has been discovered that adding EGR to a diesel reduces the specific heat ratio of the combustion gases in the stroke of the engine, i.e. the power stroke. This reduces the amount of power that can be extracted by the piston. EGR also tends to reduce the amount of fuel burned in the power stroke. This is evident by the increase in particulate emissions that corresponds to an increase in EGR.
Particulate matter (mainly carbon) that is not burned in the power stroke is wasted energy. Stricter regulations on particulate matter (“PM”) have called for further emission controls to be introduced to compensate for the PM emissions introduced by EGR. The most common is a diesel particulate filter in the exhaust system which cleans the exhaust but reduces fuel efficiency. Since EGR increases the amount of PM that must be dealt with and reduces the exhaust gas temperatures and available oxygen, these filters need to function properly to burn off soot. Automakers inject fuel and air directly into the exhaust system to keep these PM filters from becoming blocked up.
By feeding the lower oxygen exhaust gas into the intake, it has been discovered that diesel EGR systems lower combustion temperature, reducing emissions of NOx. This makes combustion less efficient, compromising economy and power. The normally “dry” intake system of a diesel engine is now subject to fouling from soot. Unburned fuel and oil in the EGR bleed, which has little effect on airflow, when combined with oil vapor from a Crankcase ventilation system (PCV system), can cause buildup of sticky tar in the intake manifold and valves. It has also been discovered to cause problems with components such as swirl flaps, where fitted.
EGR systems have also been discovered to add abrasive contaminants and increase engine oil acidity, which in turn can reduce engine longevity.
Though engine manufacturers have refused to release details of the effect of EGR on fuel economy, it has been calculated that the EPA regulations of 2002 that led to the introduction of cooled EGR were associated with a 3% drop in engine efficiency, bucking a trend of a 0.5% a year increase. Poor EGR performance occurs often, with hesitation, smoking, coughing, backfiring, and poor fuel mileage. Currently, devices only remove the EGR system, which is illegal unless used in an off road situation.
In sum, it has been discovered that EGR can be a disadvantage to engine efficiency through: 1) shortened engine lubricant life; 2) increased carbon/soot deposits throughout the engine; 3) reduced engine performance; 4) reduced fuel economy; 5) increased emissions; 6) both minor and catastrophic power train component/engine failure/reduced engine/equipment life; 7) damaged emission controls IE, EGR, turbo, diesel particulate filter; 8) cost of time, expense and inconvenience to the operator/end user; the like; and/or combinations thereof. Depending on the use of the vehicle, it has been discovered that these problems can crop up in a very short time and even in ideal conditions they may still develop. It is quite evident that, prior to the instant disclosure, researchers may be still trying to identify cause and effect of the EGR system and clearly have no solution to the problem.
As can be seen, there is a need for a solution to required EGR systems that is legal and works with the computer/ECM that controls the EGR system without having to remove the EGR system or modify the system.
Therefore, it is readily apparent that there is a recognizable unmet need for device that controls the EGR system for improved efficiency and/or life of the engine without having to remove and/or modify the EGR system.
The instant disclosure of an EGR Power Module and method of use thereof is designed to address at least some aspects of the problems discussed above.